1. Field of the Invention
The present invention relates to grit-blasting nozzles and their support fixtures. More specifically, the invention provides a grit-blasting nozzle mating with a support fixture in a manner that provides precise, identical alignment every time it is installed, and a method for precisely setting the proximity of the nozzle to the workpiece.
2. Description of the Related Art
Grit blasting is presently utilized as a step in a variety of manufacturing processes. Typically, aluminum oxide particles of a selected size are directed against the surface to be grit-blasted by compressed air, or possibly by a fluid such as water. The goal of the grit-blasting process is often to create a surface having a roughness within a certain range, which is achieved by varying the size of the alumina grit, the air pressure, the size of the nozzle opening, and/or the distance of the nozzle from the workpiece. Additionally, grit blasting may be used to precisely cut holes, for example, in silicon wafers. It is therefore necessary to precisely control these variables during the grit blasting process. Additionally, the grit blasting nozzle and hose leading to the nozzle will typically be subject to a high degree of wear due to the highly abrasive alumina grit constantly passing through them at high pressure. Therefore, it is necessary to replace the nozzle and hoses not only to achieve different surface roughnesses and/or different holes with different manufacturing processes, but also to minize machine downtime when replacing worn out components.
The time necessary to replace presently available grit blasting nozzles reduces the overall productivity of the grit blasting operation. Additionally, lack of repeatability of adjustment settings may result in increased variation in the results of the grit blasting operation, and a corresponding decrease in overall component quality. Accordingly, there is a need for a grit blasting apparatus having a nozzle. capable of being quickly installed into its fixture, and precisely aligned when it is within the fixture. Additionally, there is a need for a grit blasting apparatus having means for precisely adjusting the distance between the nozzle and the workpiece.
The present invention provides an apparatus and method for precisely aligning a grit blasting nozzle. The invention includes a movable bracket, a nozzle dimensioned and configured for rapid, precise installation within the movable bracket, and may also optionally include a fixed bracket with at least one proximity sensor.
The nozzle housing includes a flat surface and a shoulder, with each being dimensioned and configured to abut a corresponding surface on the movable fixture bracket. The nozzle also defines a means for being secured at exactly the same height with respect to the movable bracket each and every time it is utilized. Specifically, one preferred embodiment includes an angled surface on the nozzle housing dimensioned and configured to abut a spring-biased hinge within the movable bracket. When the nozzle. is inserted into the movable bracket, the pressure of the spring-biased pin against the angled surface will push the nozzle further into the bracket until the shoulder on the housing abuts the bracket, thereby precisely locating the nozzle in the same position relative to the bracket each and every time the nozzle is inserted into the bracket.
The movable bracket includes a first arm dimensioned and configured to removably secure the grit blasting nozzle, a second arm dimensioned and configured to removably secure a proximity sensor, and a grit blasting machine engaging portion dimensioned and configured for sliding motion within a desired range of distances from the workpiece. The movable bracket may, if desired, also include means for removably securing a light source dimensioned and configured to provide light to the target area of the workpiece.
If a proximity sensor is desired, then the fixed bracket will be used to support either the sensor or the sensor""s target. The fixed bracket therefore include means for being secured to the grit blasting machine in close proximity to the movable bracket, and an arm dimensioned and configured to removably secure a proximity sensor or a sensor target.
A proximity sensor secured within one bracket may be utilized to detect the distance between the proximity sensor and the proximity sensor target on the opposing bracket, from which the distance between the nozzle and the workpiece target region can be calculated. One preferred proximity sensor is an inductive resistance proximity sensor, which is well known in the art of proximity sensors.